The modern theory of evolution was enunciated by him in pretty plain terms.

He had grasped the physical law of the conservation of energy.

He solved the problem of evil by defining it to be a relative condition of imperfect development.

He denied that Paradise or a Golden Age is possible for man, or that, if possible, it can be considered higher in the moral scale than organic struggle toward completion by reconciliation of opposites through pain and labor.

He sketched in outline the comparative study of religions, which is now beginning to be recognized as the proper basis for theology.